4/17/18 Preparing for changing climate risk Professor David Karoly, Earth Systems and Climate Change Hub National Environmental Science Program, CSIRO Observed global climate change WMO, 2017 SoC, 2016 SoC, 2016 1 4/17/18 Observed changes in extremes IPCC AR5 WG1 Fig FAQ2.2 Observed Australian climate change April-Oct rain deciles 1996-2015 Oct-April rain deciles 1996-2015 SoC, 2016 2 4/17/18 Projected climate change Two paths for global warming, depending on emissions. Very low emissions gives >50% chance of warming less than 2°C Sea level rise in 2050: ~15-35cm Continues to rise for centuries after surface temperature staBilises Fig SPM.6, IPCC AR5 Synthesis Report Projected changes in Australian climate SoC, 2016 3 4/17/18 Australian climate projections Annual days above 35°C at capital cities 1981-2010 Current average CCIA 2015 CCIA 2015 City average 2006-15 (projection to 2030) (high emissions 2090) Adelaide 20.7 25.6 26 (24 to 29) 47 (38 to 57) Brisbane 13.7 12.5 18 (15 to 22) 55 (37 to 80) Darwin 11 15.4 43 (25 to 74) 265 (180 to 322) Hobart 1.6 1.8 2.0 (1.9 to 2.1) 4.2 (3.2 to 6.3) Melbourne 11 13 13 (12 to 15) 24 (19 to 32) Perth 28.8 35.4 36 (33 to 39) 63 (50 to 72) Sydney 3.1 3.0 4.3 (4.0 to 5.0) 11 (8.2 to 15) CCIA: Projections for selected Australian cities (2015) Australian climate projections Winter rainfall change (%) at capital cities Current change CCIA 2015 CCIA 2015 (projection City relative to 1986-2005 (projection to 2090, high to 2030) (%) (%) emiss.) (%) AdelaiDe -18 (-26 to -10) -6 (-16 to 6) -19 (-43 to -3) Brisbane 8 (-26 to 42) -5 (-27 to 8) -17 (-49 to +18) Darwin 7 (-126 to 140) -5 (-35 to 19) -4 (-45 to +44) Hobart -2 (-10 to 6) +1 (-6 to 10) +6 (-11 to +19) Melbourne -10 (-24 to 4) -3 (-10 to 7) -10 (-25 to +6) Perth -21 (-35 to -8) -7 (-18 to 4) -29 (-44 to -15) SyDney 23 (0 to 45) -1 (-19 to 12) -17 (-31 to +1) CCIA: Projections for selected Australian cities (2015) 4 4/17/18 Changes in heatwaves for different levels of future global warming Marked increases in number of heatwave days and peak intensity, ~50% more than mean warming From Perkins-Kirkpatrick, 2017 Fire weather DJF Significant trends towards more Long-term change: dangerous conditions in SE days > 90th percentile MAM Australia (from 1983-99 to 2000-16) Ø Earlier start to the fire season in many parts of Australia JJA SON From Dowdy (2017), JAMC 5 4/17/18 Fire weather FFDI deciles for Feb 2017 Significant trends towards more dangerous conditions in NSW Ø Many recent events are worse than conditions experienced previously. Sea-level rise and flood frequency • Impacts of sea-level rise are felt strongly during extreme events • Sea levels have risen by ~ 0.1 m since 1970 • Projected sea-level rise for RCP 8.5 relative to 1986-2005 2050 : 0.24 [0.15-0.32] m 2100 : 0.44 [0.44-0.96] m Data sources: McInnes et al, 2015 6 4/17/18 Frequency of inundation will increase with sea-level rise • Change in frequency depends on the characteristics of extreme events at a given location • For Williamstown, a 0.5 m sea-level rise is expected to increase the frequency of exceedances by a factor of ~ 130 times • i.e. a 1-in-100 year event will occur more than once per year under a 0.5 m sea- level rise Data source: IPCC AR5, Chapter 13, Figure 13.25 Severity of inundation will increase with sea-level rise 2100 inundation from extreme event (1-in-100 year stormtide = 1.09 m) + median SLR for RCP 8.5 = 0.69 m SLR 2100 inundation from extreme event (1-in-100 year stormtide = 1.09 m) + upper SLR for RCP 8.5 = 0.96 m SLR http://coastalrisk.com.au/viewer Data sources: http://www.climatechangeinaustralia.gov.au/en/ 7 4/17/18 Summary • Climate change has already led to significant changes in climate risks and will continue to do so for the next 30-100 years or more • Most confident projected changes are for increases in heat waves, severe fire weather and coastal flooding, less certainty in many other extremes • For cities in southern Australia, observed changes to 2006-2015 in winter rainfall and days above 35C are already at or above the median changes for 2030. This suggests that hotter and drier projections agree better with recent observed changes than the model median for this region FOR MORE INFORMATION Prof David Karoly [email protected] www.nespclimate.com.au The Earth Systems and Climate Change Hub is funded by the Australian Government’s National Environmental Science Program, with co-investment from the following partner agencies 8 4/17/18 References • Bureau of Met/CSIRO State of the Climate 2016 www.bom.gov.au/state-of- the-climate • IPCC AR5 Climate Change 2013: The Physical Science Basis, IPCC AR5 Climate Change 2014: Synthesis Report www.ipcc.ch • Climate change in Australia: Projections for selected Australian cities, CSIRO, 2016 https://www.climatechangeinaustralia.gov.au/en/ • McInnes, K.L., et al., 2015: Sea-level rise projections for Australia: Information for impact and adaptation planning. AMOJ, 65, 127–149. Choices on future climate change Two paths for fossil fuel CO2 emissions Two paths for future gloBal warming Fig 5.1, The Science of Climate Change, AAS 2010 Based on Meinshausen et al. 2009 9 4/17/18 From The Age 31/10/17 10.